非晶合金Zr55Al10Cu30Ni5在3.5%NaCl溶液中的电化学行为

利用电化学极化曲线方法和电化学阻抗（EIS）技术研究了非晶合金Zr55Al10Cu30Ni5在3.5%NaCl溶液中的电化学行为。极化曲线测试结果表明，非晶合金Zr55Al10Cu30Ni5在3.5%NaCl溶液中具有很好的耐蚀性能，阳极过程表现出钝化特征，当极化电位很高时，非晶合金出现了点腐蚀。电化学交流阻抗测试表明，在阴极极化，开路电位和钝化电位下，非晶合金的Nyquist图由单容抗构成，具有很高的电荷转移电阻，表现出优良的耐蚀性，在点蚀电位附近和点蚀电位区EIS分别有两个时间常数和三个时间常数，非晶合金在3.5%NaCl溶液中浸泡12h后，耐蚀性能有所下降。     

Cu对TiNi记忆合金耐腐蚀性能的影响

用电化学极化方法研究了Cu含量及溶液pH值对Ti50Ni50-xCux合金在1%NaCl溶液中的耐蚀性的影响。结果表明,Cu的加入可显著提高合金的再钝化电位,而对点蚀电位在x<6时则无明显影响。溶液pH值升高时,点蚀电位提高。而再钝化电位则不受pH值影响。     

含Mo和Ta作为β稳定剂元素的Ti合金在牙科应用中的电化学行为

研究具有相同Mo质量分数（12%）的Ti12Mo和Ti60Ta合金以及当前常用的Cp-Ti金属生物材料在牙科应用中的电化学行为。采用电化学方法,在37°C下,研究样品在人工唾液以及加氟人工唾液（含0.1%F-）两种电化学媒质中的电化学性能,如开路电位、动电位极化曲线和电化学阻抗。在牙膏、牙科凝胶和牙科冲洗等方面,通常含有氟化物以防止龋齿和缓解牙齿敏感。观察在两种媒质中所有钛合金样品的电化学行为,结果表明：在两种电化学媒质中,Ti60Ta合金具有比Ti12Mo和Cp-Ti更优异的抗腐蚀性能。     

XPS研究Ti32Mo在浓盐酸溶液中钝化膜结构

用XPS研究了Ti32Mo在70℃,4 mol/L盐酸溶液阳极电位为+0.2 V和+0.9 V时的钝化膜结构和组成.结果表明,钝化膜是由表层和过渡层组成的双层结构.对于阳极电位为+0.2 V的试样,钝化膜富集因子f(Mo)随溅射深度由最外层的1.60变化到8 nm时的1.20;而对于阳极电位为+0.9 V的试样,钝化膜富集因子f(Mo)在1.1-1.22之间变化.钝化膜的表层还可以分为两个亚层Ⅰ和Ⅱ.钝化膜的组成主要是Ti和Mo各种价态的氧化物、氢氧化物和氯化物.     

化学镀Ni-P合金在氯化物溶液中的化学钝化

本文对化学镀Ni-P合金在3.5%NaCl溶液中的阳极行为进行了研究。运用动电位极化技术和电化学阻抗谱(EIS)技术对活化区和钝化区的测量结果表明:过电位与呈线性关系,但不同电位区,其斜率相差较大。在活化区,界面电容C随过电位的增大而减小,而在钝化区,C维持恒定。对表面膜的XPS分析证实:在活化区形成有磷酸盐膜,保护性差,不能有效地抑制溶解过程;而当表面吸附有H2PO2阴离子时,合金进入化学致钝的钝化区.     

钛钼合金在盐酸溶液中形成的钝化膜研究

应用XPS和电化学测量技术研究了Ti-15Mo合金在70℃的1mol/L和4mol/LHCl溶液中不同阳极极化条件下生成的钝化膜。结果表明,钝化膜是双层结构,由表层和过渡层组成。在低极化电位(0.000和-0.100V)下膜表层较厚(4nm),富集Mo。在高极化电位(+0.900V)下膜表层较薄(2nm),贫Mo。在钝化膜内含有较多Cl~-,而且Cl~-分布很深。推测Cl参加了膜的生成反应,生成了Ti和Mo的含氯和氧的化合物。     

HCO_3~-对J55钢在1%NaCl溶液中腐蚀行为的影响

用动电位极化曲线、扫描电镜(SEM)和电化学阻抗谱技术(EIS)研究了HCO3-对J55钢在1%NaCl溶液中的腐蚀行为的影响.结果表明,HCO3-浓度越大阳极反应速率越小.当HCO3-浓度高于0.060 mol/L时HCO3-呈现出钝化特征.随着NaCl溶液中HCO3-量的增加,Rt增大,腐蚀速度减小.J55钢在含NaHCO3为374 mg/L的溶液中腐蚀的电化学阻抗谱中出现了感抗,在含NaHCO3为30 g/L的溶液中腐蚀的的电化学阻抗谱出现了Warburg阻抗,在含NaHCO3为1、5和8.4g/L的溶液中腐蚀的电化学阻抗谱仅出现单容抗弧特征.随着HCO3-浓度的增大阴极反应速率越来越大.极化电位为-0.9 V附近,随着极化电位的增大极化电流出现了突增.     

H2S水溶液中的腐蚀与缓蚀作用机理的研究Ⅱ.碳钢在碱性H2S溶液中的阳极钝化及钝化膜破裂

通过极化曲线和交流阻抗谱 (EIS)测定 ,对低碳钢在碱性H2 S溶液中的钝化及钝化膜破裂过程进行了研究。结果表明 ,相同pH值下 ,除氧碱性溶液中加入H2 S,对碳钢的钝化具有一定的促进作用 ;在阳极极化下 ,钝化初期阻抗谱具有两个时间常数 ,表现出不完全钝化的特征 ;随极化电位的升高 ,钝化膜逐渐完整 ,阻抗呈单一容抗弧特征 ,容抗弧半径逐渐增大 ;当极化电位高于 - 690mV时 ,由于电极表面HS 同OH 的竞争吸附和放电作用 ,导致电极表面钝化膜发生酸性溶解 ,并生成硫化物斑点 ,极化电阻显著下降 ,当极化电位高于 - 635mV时 ,钝化膜发生破裂 ,电极表面有大量硫化物生成     

经等离子体源渗氮的奥氏体不锈钢耐蚀性能研究

对AISI 316奥氏体不锈钢进行了450℃×6 h的等离子体源渗氮,获得了厚度约为17μm、氮浓度高达20%(原子分数)的面心立方γ_N相渗层。采用阳极极化和电化学阻抗谱(EIS)研究了γ_N相在3.5%NaCl溶液中的电化学腐蚀行为。结果表明,γ_N相的阳极极化曲线呈现出活化溶解-自钝化-过钝化溶解过程,γ_N相未发生点蚀。与奥氏体不锈钢原材料相比,γ_N相的自腐蚀电位高226 mV,钝化电流密度低了近一个数量级。钝化膜电化学阻抗谱的容抗弧直径增大,相位角变宽,采用等效电路R_s-(R_(ct)//CPE)拟合的电荷转移电阻R_(ct)增大,双电层电容C_(dl)降低,耐蚀性能显著提高。随着渗层浸入3.5%NaCl溶液中的时间的延长,γ_N相钝化膜的耐蚀性改善,发生点蚀的倾向性减小。     

热处理对CuAlNi形状记忆合金腐蚀性能的影响（英文）

通过开路电位测试、极化技术和电化学阻抗谱法研究热处理对CuAlNi形状记忆合金腐蚀性能的影响,测试条件为:0.9%NaCl溶液,pH=7.4和T=37°C。对比研究铸态和分别在850、885和920°C退火+水冷淬火后的CuAlNi合金样品。电化学阻抗谱法的结果显示,热处理后的CuAlNi合金其电荷转移电阻和表层电阻增加、双层表面和表层电容值降低,说明与铸态合金相比,热处理提高了合金的耐腐性。极化电阻的增加和腐蚀电流密度的降低也表明热处理对CuAlNi合金的耐腐蚀性能有利。对极化曲线测试后的样品表面进行光学显微镜、SEM/EDX和XRD分析。结果表明,电极表面发生点蚀,腐蚀产物为Cu Cl_2、Al Cl_3和Cu_2Cl(OH)_3。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.